UNIT 14 ENVIRONMENTAL CHEMISTRY
Environmental pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings.
A substance which causes pollution is known as a pollutant.
Tropospheric pollution occurs due to:
Causes of water pollution:
Green chemistry is a way of thinking and is about utilising the existing knowledge and principles of chemistry and other sciences to reduce the adverse impact on environment. Green chemistry is a production process that would bring about minimum pollution or deterioration to the environment.
Green chemistry in day-to-day lives
UNIT 13 Hydrocarbons
Compounds consisting of carbon and hydrogen only are known as hydrocarbons.
These are saturated open chain hydrocarbons containing carbon-carbon single bond.
Alkenes are unsaturated hydrocarbons containing at least one double bond.
Isomerism: Alkenes show both structural and geometrical isomerism
Alkynes are unsaturated hydrocarbons which contain at least one triple bond between two carbon atoms.
These hydrocarbons are also known as arenes. Most of these compounds possess a pleasant odour and hence called aromatic.
Most of these compounds contain benzene ring. Benzene ring is highly unsaturated. Aromatic compounds containing benzene ring are known as benzenoids and those not containing a benzene ring are known as non-benzenoids.
UNIT 12 ORGANIC CHEMISTRY
CLASSIFICATION OF ORGANIC COMPOUNDS
1. Acyclic or open chain compounds: These compounds are also called aliphatic compounds and consist of straight or branched chain.
2. Alicyclic or closed chain or ring compounds: These compounds contain carbon atoms joined in the form of a ring.
The phenomenon of existence of two or more compounds having the same molecular formula but different properties is known as isomerism. Such compounds are called isomers.
1. Structural isomerism: When compounds have the same molecular formula but different structures, it is called structural isomerism. Types of structural isomerism are:
TYPES OF ORGANIC REACTIONS:
UNIT 11 THE p-BLOCK ELEMENTS
GROUP 13 ELEMENTS: THE BORON FAMILY
Elements: Boron, Aluminium, Gallium, Indium, Thallium
Electronic configuration: The outer electronic configuration of these elements is ns2 np1.
Atomic radii: Atomic radii increase on going down the group.
Ionization enthalpies: The ionization enthalpies do not decrease smoothly down the group.
Electronegativity: Down the group, electronegativity first decreases from B to Al and then increases marginally.
GROUP 14 ELEMENTS: THE CARBON FAMILY
Elements: Carbon, Silicon, Germanium, Tin, Lead
Electronic configuration: The valence shell electronic configuration of these elements is ns2 np2.
Covalent radius: There is a considerable increase in covalent radius from C to Si. From Si to Pb, there is a small increase in radius.
Ionization enthalpy: The first ionization enthalpy of group 14 members is higher than the corresponding members of group 13.
Electronegativity: The elements of this group are slightly more electronegative than group 13 elements.
UNIT 10 THE s-BLOCK ELEMENTS
GROUP-1 ELEMENTS: ALKALI METALS
Electric configuration: All alkali metals have one valence electron, 1s2.
Atomic and ionic radii: The alkali metal atoms have the largest sizes in a particular period of the periodic table.
Ionization Enthalpy: The ionization enthalpies of the alkali metals are considerable low and decrease down the group.
Hydration Enthalpy: The hydration enthalpies of alkali metal ions decrease as we move down the group.
Physical Properties: All the alkali metals are silvery white, soft and light metals. These elements have low density which increases down the group. The melting and boiling point of alkali metals are low.
GROUP-2 ELEMENTS: ALKALINE EARTH METALS
Electronic configuration: These elements have two electrons in the s-orbital of the valence shell. Their general configuration is ns2.
Atomic and ionic radii: The atomic and ionic radii of the alkaline earth metals are smaller than those of the corresponding alkali metals in the same periods.
Ionization enthalpies: Alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms.
Hydration enthalpies: The hydration enthalpies of alkaline earth metals ions decrease with increase in ionic size down the group.
UNIT 9 HYDROGEN
Hydrogen is the first element in the periodic table.
Its electronic configuration is 1s1.
Occurrence: Dihydrogen is the most abundant element in the universe. It is the principal element in the solar atmosphere.
Isotopes of hydrogen: Hydrogen has three isotopes: protium, deuterium and tritium
PROPERTIES OF DIHYDROGEN:
USES OF DIHYDROGEN
UNIT 8 REDOX REACTIONS
OXIDATION: Loss of electron(s) by any species
REDUCTION: Gain of electron(s) by any species
OXIDISING AGENT: Acceptor of electron(s)
REDUCING AGENT: Donor of electron(s)
A reaction in which oxidation and reduction takes place simultaneously is called a redox reaction.
It denotes the oxidation state of an element in a compound ascertained according to a set of rules formulated on the basis that electron in a covalent bond belongs entirely to more electronegative element.
TYPES OF REDOX REACTIONS
1. Combination reactions
UNIT 7 EQUILIBRIUM
Equilibrium is a state where the rate of evaporation is equal to the rate of condensation.
The mixture of reactants and products in the equilibrium state is called an equilibrium mixture. When there is no change in the concentration s of either of the reactants or the products, the stage is called dynamic equilibrium. At dynamic equilibrium, the rates of forward and backward reaction become equal.
GENERAL CHARACTERISTICS OF EQUILIBRIA INVOLVING PHYSICAL PROCESSES
For physical processes, the following characteristics are common to the system at equilibrium:
LAW OF CHEMICAL EQUILIBRIUM
At a given temperature, the product of concentrations of the reaction products raised to the respective stoichiometric coefficient in the balanced chemical equation divided by the product of concentrations of the reactants raised to their individual stoichiometric coefficients has a constant value. This is known as the Law of chemical equilibrium or Equilibrium law.
APPLICATIONS OF EQUILIBRIUM CONSTANNTS
The important features of equilibrium constants are:
UNIT 6 THERMODYNAMICS
SYSTEM AND ITS SURROUNDINGS
System: A system in thermodynamics refers to that part of universe in which observations are made.
Surroundings: The surroundings include everything other than the system.
TYPES OF SYSTEM
1. Open system
THE STATE OF THE SYSTEM
The state of a thermodynamic system is described by its measurable or macroscopic (bulk) properties. The state can be described by quoting its pressure, volume, temperature, etc. Variables like these are called state variables or state functions because their values depend only on the state of the system and not on how it is reached.
THE INTERNAL ENERGY AS A STATE FUNCTION
The internal energy of a system may change due to heat passing in or out of the system, work done on or by the system, or if matter enters or leaves the system.
Entropy is a measure of disorder or randomness in a system.